Estimation of Arctic polar vortex ozone loss during the winter of 1999-2000 using vortex-averaged airbone differential absorption lidar ozone measurements referenced to N2O isopleths

Abstract

The NASA Langley UV differential absorption lidar (DIAL) system flew on the NASA DC-8 aircraft during the Stratospheric Aerosol and Gas Experiment (SAGE) III Ozone Loss and Validation Experiment/Third European Stratospheric Experiment on Ozone 2000 (SOLVE/THESEO 2000) mission from 30 November 1999 to 15 March 2000. The UV DIAL system measured ozone (O3) profiles at altitudes from about 1 km above the aircraft up to about 26 km with a vertical resolution of 750 m and a horizontal resolution of 70 km below 19 km and 140 km above 19 km. In comparison with electrochemical concentration cell ozonesonde profiles, the UV DIAL O3 measurements agreed to within 5% up to 20 km and 10% from 20 to 25 km. Ozone loss during the season was determined using the UV DIAL O3 data along with air mass subsidence determined using N2O as a conservative tracer at five levels from 50 to 250 ppbv [Greenblatt et al., 2002]. O3 mixing ratios were determined inside the polar vortex, away from the collar region along these five levels during the mission. The maximum O3 loss determined from 30 November to 12 March was 1.55 ± 0.3 ppmv at the 440-450 K potential temperature (Θ) level, while the loss there between 20 January and 15 March was 1.3 ± 0.3 ppmv. These results are comparable to many of the other reported losses for these periods, but lower than several. Some of the determinations of higher losses used a different method to determine descent during the season. These results indicate that a series of vertical profiles of O3 that sample much of the vortex during the winter, along with determinations of the descent of air masses inside the vortex, can give a reasonable estimate of the O3 changes during the season.